What's the difference...

We have a robin in our back yard that has built a nest, and her eggs just hatched. Zoe and I decided to go to the library to learn about Robin's, so here is a bit of our conversation today as we were looking through books about birds...
Me: What differences do you see between the sparrow and the Robin?
Zoe: The sparrow looks fluffy
Me: Ok. What about their tummies?
Zoe: Well...um...the Robin's tummy is orange, the other one is like this (hands making circular motion) and your tummy is squeeshy.

Appreciate the added bonus answer